linux-kernel - [PATCH v2] cifs: avoid NULL pointer dereference in dbg call

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Message-Id: <20250319142858.2166-1-adiupina@astralinux.ru>
Date: Wed, 19 Mar 2025 17:28:58 +0300
From: Alexandra Diupina <adiupina@...ralinux.ru>
To: Steve French <sfrench@...ba.org>
Cc: Alexandra Diupina <adiupina@...ralinux.ru>,
	Paulo Alcantara <pc@...guebit.com>,
	Ronnie Sahlberg <ronniesahlberg@...il.com>,
	Shyam Prasad N <sprasad@...rosoft.com>,
	Tom Talpey <tom@...pey.com>,
	Bharath SM <bharathsm@...rosoft.com>,
	Aurelien Aptel <aaptel@...e.com>,
	Pavel Shilovsky <pshilov@...rosoft.com>,
	linux-cifs@...r.kernel.org,
	samba-technical@...ts.samba.org,
	linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org
Subject: [PATCH v2] cifs: avoid NULL pointer dereference in dbg call

cifs_server_dbg() implies server to be non-NULL so
move call under condition to avoid NULL pointer dereference.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: e79b0332ae06 ("cifs: ignore cached share root handle closing errors")
Signed-off-by: Alexandra Diupina <adiupina@...ralinux.ru>
---
v2: fix indentation
 fs/smb/client/smb2misc.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/smb/client/smb2misc.c b/fs/smb/client/smb2misc.c
index f3c4b70b77b9..c02aab58aade 100644
--- a/fs/smb/client/smb2misc.c
+++ b/fs/smb/client/smb2misc.c
@@ -816,11 +816,12 @@ smb2_handle_cancelled_close(struct cifs_tcon *tcon, __u64 persistent_fid,
 		WARN_ONCE(tcon->tc_count < 0, "tcon refcount is negative");
 		spin_unlock(&cifs_tcp_ses_lock);
 
-		if (tcon->ses)
+		if (tcon->ses) {
 			server = tcon->ses->server;
-
-		cifs_server_dbg(FYI, "tid=0x%x: tcon is closing, skipping async close retry of fid %llu %llu\n",
-				tcon->tid, persistent_fid, volatile_fid);
+			cifs_server_dbg(FYI,
+					"tid=0x%x: tcon is closing, skipping async close retry of fid %llu %llu\n",
+					tcon->tid, persistent_fid, volatile_fid);
+		}
 
 		return 0;
 	}
-- 
2.30.2